Motor vehicles such as cars, trucks, vans, sport utility vehicles, buses and the like, include seats which are desirably adjustable. It is generally desirable to provide such a motor vehicle seat with a backrest that is adjustable to various degrees of inclination, that is, multiple positions to provide versatility and comfort for various users. It is further desirable to adjust the backrest in a simple manner and to securely lock the backrest in its various locked positions.